Species delineation, phylogeography and conservation of temperate perches (Actinopterygii: Percichthyidae) from an endemism and climate change hotspot

Context The south-western corner of Australia is a biodiversity hotspot that includes a freshwater fauna with a high proportion of endemic species. The temperate perches comprise nearly half of the obligate freshwater fishes of the region, representing important components of local ecosystems and are of significant conservation concern. Aims Provide a spatially comprehensive molecular genetic assessment of species boundaries and major substructure for all local members of the family to better understand the interplay of ecology and environment across a common landscape. Methods Nuclear markers (allozymes) and matrilineal (cytb) datasets were generated to infer genetic groupings and any instances of hybridisation or introgression in relation to the current taxonomy, regional geography and ecological understanding. Key results There were contrasting patterns of diversification across genera, with Nannoperca housing four likely species-level splits, Nannatherina having three distinct geographically and ecologically separated subpopulations, and Bostockia comprising several refugial subpopulations that appear partially introgressed. Repeated genetic patterns were identified across particular biogeographic features, most notably the Margaret River and Shannon River. Conclusions This study highlighted the value of comparative range-wide molecular studies to inform taxonomy, ecology and conservation planning. Implications These analyses pave the way for taxonomic revision, management of key habitat refuges, and other conservation actions.